A multi-bearer network (“MBN”), is a network having the capability to transmit a data packet via one of several alternative bearer network types to mobile terminals. Each mobile terminal is preferably able to communicate with a plurality of bearer networks (“BN”). The bearer networks are known to one skilled in the art and typically comprise at least one bi-directional bearer network (e.g., GSM, GPRS, UMTS, WLAN, Bluetooth, etc.) and at least one unidirectional or broadcast bearer network (e.g., DAB, DVB, etc.). The DAB and DVB broadcast bearer networks are commonly referred to as DxB. The DxB networks are the principal bearer networks for down-link traffic. A mobile terminal uses the bi-directional (up-link) bearer network primarily for accessing the services of the DxB networks, although some bi-directional bearer network, most notably UMTS, can be used for down-link traffic at a moderately high speed. Moreover, the other bi-directional bearer networks mentioned above may be used to transmit services that do not require significant bandwidth. The bearer networks are geographically overlapping, and a mobile terminal may have access to all bearer networks simultaneously. MBN's are well-known and described in detail in WO 01/76286 A1, entitled “Architecture and Packet Routing in a Multi-Bearer Type Network” and WO 01/74108 A1, entitled “Handover in a Wireless Mobile IP Network”, copies of which are incorporated herein by reference.
FIG. 1 shows an exemplary bearer network A 100a and an exemplary bearer network B 100b of a Multi-Bearer Network 100 (MBN), having at least one transmitter 102a for use in transmitting service data from bearer network A 100a, and having at least one transmitter 102b for use in transmitting service data from bearer network B 100b, to at least one mobile terminal 104. Service data may include streaming MP3 data, periodically updated weather reports sent over IP, IP services such as multicast services or unicast services, cell to session mappings or IP component mappings, or the like. Bearer network A 100a packetizes its respective service data and sends it (step 101a) to at least one transmitter 102a for transmission to the mobile terminal 104 in a manner well known to those skilled in the art. Additionally, bearer network B 100b also packetizes its respective service data and sends it (step 101b) to at least one transmitter 102b for transmission to the mobile terminal 104 in a manner well known to those skilled in the art. The mobile terminal 104 may be capable of receiving packetized service data from only a single bearer in the network or, alternatively, may be a “hybrid” terminal capable of receiving packetized service data from a plurality of bearer networks in a MBN 100.
Each multi bearer network 100 that transmits service data, typically does so on a plurality of channels, where each service is assigned to a particular channel. A channel may be a frequency, a program identifier (“PID”), a media access control (“MAC”) address, or the like. In addition to the service data, the multi bearer network 100 also transmits service announcements to enable a mobile terminal 104 to identify the service that a multi-bearer network 100 is transmitting on a channel. Several methods of transmitting service announcements have been proposed. FIG. 2 illustrates one such method, wherein a multi-bearer network 100 uses X channels 200 to transmit service data to a mobile terminal 104. It is assumed that each mobile terminal 104 initially tunes to a random channel upon powering up. The channel may be a specific frequency, but need not be so limited. As shown in FIG. 2, for each channel, a service “S” and a service announcement “A” identifying the service transmitted on the same channel. In other words, the service S1 and the service announcement A1 identifying S1 are transmitted on channel 1, the service S2 and the service announcement A2 identifying S2, are transmitted on channel 2, etc. In order to identify the services available on all X channels 200, the mobile terminal 104 will tune to a first channel, access the service announcement on that channel, identify the service available on that channel, and then tune to another channel to determine the service available on that channel. This process of tuning, accessing and re-tuning is repeated until all channels carrying services that the mobile terminal 104 is able to receive have been tuned to, and their respective services identified. Assuming that it requires “Y” seconds to identify the services available on a given channel, and that it requires “T” seconds to jump from one channel to another channel, then the total learning time “t” for the mobile terminal 104 to identify all of the services available is t=X*(Y+T) seconds.
FIG. 3, illustrates another exemplary method of transmitting service announcements. As shown in FIG. 3, a multi-bearer network 100 uses X channels 300 to transmit service data to a mobile terminal 104. As in the previous method, the mobile terminal 104 initially tunes to a random channel upon powering on. Unlike the previous method, however, one channel contains all of the service announcements, A1 through AX, for all X channels 300 that provide a service, S1 through SX, respectively. This channel is referred to as the “all-announcement” channel 301. The probability that the mobile terminal 104 will randomly select the all-announcement channel 301 is 1/X, assuming that the process of selecting a frequency is truly random. As in the method of FIG. 2, the mobile terminal 104 tunes to each channel for Y seconds to determine if it has tuned to the all-announcement channel 301. The time required for the mobile terminal 104 to tune from one channel to another channel is T seconds. Therefore, the minimum learning time, defined as “tmin”, is greater than or equal to Y seconds, and the maximum learning time, “tmax” is less than or equal to X*(Y+T) seconds. Taking the average of tmin and tmax to be the expected learning time for the mobile terminal 104 to identify the all-announcement channel 301, the expected learning time is (Y+X*(Y+T))/2. This, however, results in only a marginal improvement in minimizing the expected learning time.
FIG. 4 illustrates yet another exemplary method of transmitting service announcements. In FIG. 4, there are X channels 400. Each channel, however, contains the service announcements, A1 through AX, for all of the services S1 through SX provided on the X channels. In other words, channel 1 contains the service announcements, A1 through AX, for channel 1 through channel X respectively, along with the service S1 for channel 1, channel 2 contains the service announcements, A1 through AX, for channel 1 through channel X, along with the service S2 for channel 2, etc. Therefore, the channel that the mobile terminal 104 initially selects upon being powered on will contain all of the necessary service announcements. This eliminates the additional learning time associated with the methods discussed above in connection with FIGS. 2 and 3. However, in the method of FIG. 4, the additional bandwidth that the service announcements, A1 through AX, consume is significant, as can readily be seen by comparing FIGS. 2-4.
Solutions other than those discussed above are less automated. For example, in many European countries, such as Italy, upon leaving from an airplane and turning on a mobile phone, the user will receive an SMS message from the network operator such as “Call 12233 to get information on services in Italy”. The user can then call the number provided to receive information on the available services.
It is clear that there is a need to overcome the inefficiency of the aforementioned methods.